CVE-2026-43026netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent
Updated under an hour ago ()
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It affects Linux and 4 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from the prior allocation.
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 076a0ca02644657b13e4af363f487ced2942e9cb before a5a89db6981a1ddf2314bf50cb49db5a3146185f; 076a0ca02644657b13e4af363f487ced2942e9cb builds before 1c2ebdeff8d088a2e47ae25d7b38447249adace2; from 076a0ca02644657b13e4af363f487ced2942e9cb before a64b7bf84b4d5ea54218c5d374ec87fff9000f43; from 076a0ca02644657b13e4af363f487ced2942e9cb before 2898080c054ea4d6ddfaaf21bbedbc229a9a8376; from 076a0ca02644657b13e4af363f487ced2942e9cb before fd002ff2ea030cbfb0188a11b3c60ce7f84485f4; from 076a0ca02644657b13e4af363f487ced2942e9cb before 929f7a9a7aad9404a5867216c3f8738232355b38; from 076a0ca02644657b13e4af363f487ced2942e9cb before bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36; from 076a0ca02644657b13e4af363f487ced2942e9cb before 35177c6877134a21315f37d57a5577846225623e | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 3.4 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.134; from 6.7 before 6.12.81; from 6.13 before 6.18.22; from 6.19 before 6.19.12; 7.0; and 5 more ranges | NVD |
References
- https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185fpatch
- https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2patch
- https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43patch
- https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376patch
- https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4patch
- https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38patch
- https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36patch
- https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623epatch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.